Question : A sphere of mass 𝑚 is tied to end of a string of length 𝑙 and rotated through the other end along a horizontal circular path with speed 𝑣. The work done in full horizontal circle is
(A) 0
(B) \dfrac{mv^{2}}{l}.2\pi l
(C) mg\cdot 2\pi
(D) \left( \dfrac{3v^{2}}{l}\right) \cdot \left( l\right)
Answer : option (A)
Solution :
